Gold doped ruby glasses are classic examples of glass-metal composites that have been investigated for their striking optical properties. Manipulation of such glass-metal composites has been performed to alter the optical properties, such as to polarize or otherwise filter light.
In another field, transparent conducting oxides (TCO) are known to be used as a coating layer in a variety of technologies. For example, Indium-Tin-Oxide (ITO), a subcategory of TCO, is becoming increasingly useful for a growing number of high tech applications, including liquid crystal display (LCD), phones, aircraft windshields, transparent antistatic panels, de-icing and heater applications, among others. However, Indium is in limited supply, as there is barely enough to meet U.S. needs, let alone global demands. Therefore, there exists a continuing and unmet need for conductive materials that provide the benefits of TCOs such as ITO, but that do not require rare metals such as Indium.